I've only seen one single mention of any liver toxicity on one site, and never anywhere else. My husband wanted to try the salve for cirrhosis of the liver, so we did. Over several years he did 4 treatments with it, even while he was still drinking. That began in 1986. When he went back to rehab in 2004, this liver was perfectly fine. No sign of disease. But on his second or third treatment, it threw him into a systemic detox and he was so sick he couldn't even keep down water. We drove 200 miles to a naturopath, who said, "yes, indeed, he's detoxing." But she did give him liver glandular protomorphogens from Standard Process to support his liver function. During the time of this detox, he was passing black tarry liquid through the bowels.
We didn't know about taking bloodroot or salve in those days, so no idea about the effects, nor do I know if there is much known liver toxicity in bloodroot.
I just found a site--real anti-alt med but with information. It says in animal testing, HIGH DOSES showed some liver toxicity. But...strong cancer treatment indications.